Cryptic diversity of the ‘cosmopolitan’ harpacticoids copepod Nannopus palustris: genetic and morphological evidenceстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:Nannopus palustris Brady, 1880 is a free-living widely distributed harpacticoid
copepod, which has been formerly assumed to be a single, cosmopolitan but highly
variable species. We compared several geographically distant N. palustris populations
in terms of their morphology and genetics. Populations from the White Sea (WS), the
North Sea (NS), the Black Sea (BS) and two sympatric morphs from South Carolina,
USA (SC notched and SC straight morphs), were considered. The NS, BS and to a lesser
extent SC notched specimens were morphologically similar and partly coincided to
the ‘canonical’ description of the species. By contrast, WS population showed remarkable
anatomical and morphometric peculiarities that correspond to some earlier
descriptions. Genetic analyses of mitochondrial (cytochrome b) and nuclear (28S
rDNA) genes demonstrated the significant distinctness among WS, both SC and (NS
+BS) populations, the latter two being genetically indistinguishable. Concordance
between mitochondrial and nuclear gene trees and morphological data supports that
N. palustris is in fact composed of several pseudo-sibling species, which are genetically
and morphologically divergent. Neither correlation between genetic divergence
and geographical distance nor significant intrapopulation diversity was found for these
species. Taxonomic status, distribution and phylogenetic relationships of the species
within the Nannopus genus need to be reconsidered. A further subdivision of species
complexes might have important implications for the analysis of biodiversity of benthic
copepods and consequently for the interpretation of their (species-specific)
ecological function.